This invention relates to a dispenser for dispensing glue in small quantities from a collapsible tube or other container through a nozzle mounted on the collapsible tube, and includes a nozzle valve for immediately closing the nozzle when the glue is not to be dispensed from the tube.
Collapsible tubes have been in common use for the purpose of storing and dispensing pastes such as glue and other substances. The collapsible tubes usually include an externally threaded spout and an internally threaded cap that closes the spout to keep the glue in the tube and to prevent hardening of the glue within the tube. The collapsible tubes are desirable for dispensing glue since the tubes can be completely filled with the glue and the tube closed without trapping air inside the tube, and when the glue is to be dispensed from the tube the tube is squeezed to urge the glue through the open spout and no air is required to enter the tube to dispense the glue. This prevents the air from contacting the glue inside the collapsible tube.
The new fast hardening glues such as cyanoacrylate harden within about one minute after exposure to the atmosphere. Thus, it is imperative that the glue be stored in an air-free environment within the collapsible tube dispenser so as to maintain a long shelf life prior to its sale, and after its sale and when the cap is removed to open the spout and a portion of the glue dispensed from the tube it is imperative that the cap be immediately placed back on the spout of the tube to prevent air from entering the tube and from hardening the glue in the tube.
It has become customary to equip the tubes of fast hardening glues with special nozzles which are elongated and have very small nozzle openings that tend to minimize the area of contact between the glue remaining inside the collapsible tube and the air outside the nozzle. Moreover, some of the tubes are manufactured with sealing diaphragms about the opening of the spout and the cap or nozzle is removable from the spout of the collapsible tube so that the sealing diaphragm can be exposed an punctured and the cap or nozzle quickly inserted on the spout. Of course, it is difficult to puncture the sealing diaphragm without inadvertantly dispensing some of the glue from the collapsible tube, and once the special nozzle is inserted back on the spout, even the relatively small nozzle opening permits at least some air-glue contact and hardening of the glue within the nozzle and collapsible tube. Also, air is sometimes inadvertently aspirated from outside the nozzle, inwardly through the small opening of the nozzle and into the nozzle and the collapsible tube during handling of the dispenser, causing hardening of the glue within the dispenser.